According to Kingsport Police Department Det. Cpl. Frank Light, the bills are "real" money -- but not of the denomination they purport to be. Counterfeiters are bleaching $5 bills and, through the use of modern printers, adorning them as 100s.

Therefore, since the bills are real, pens that businesses use to mark money and determine its legitimacy will not be effective. Light urges money handlers to hold bills up to the light and search for their watermarks, or security strips that run vertically across the face of the bills.

"If it's Franklin on the bill, make sure Franklin is the watermark," Light said. "What we're running across is they're making a $100 bill and putting Franklin's face on it, but the watermark is Lincoln because they're bleaching out a five."

While Kingsport police have only encountered illegitimate $100 bills thus far, they've gathered information indicating $5 bills are also being altered to pass as 20s and 50s. The counterfeiting technique popped up in Kingsport about a month ago, and detectives are in the process of contacting other local law enforcement agencies to exchange information.

Light said Johnson City has seen a rash of counterfeit bills as of late, but does not yet know if the same bleaching and altering technique is being used.

"As technology progresses with the pens to determine whether or not they're counterfeit, (counterfeiters) are progressing as well," Light said.

"With the printers and inks that are out, it presents a problem."

Light urges businesses that encounter fake money no to return customers the bills, but keep them and call police.

The fake bills reported to police on Wednesday were from by Burger King, 1209 North Eastman Road, and Wholesale Supply Group, 2746 East Center Street.

On Monday police arrested two men for allegedly attempting to pass fake bills; in one instance at Krispy Kreme, a suspect successfully received $98.51 in change. The wife of one of those men was arrested the week prior for the same crime.